Crosslinking agent and curable composition

Abstract

The invention provides a crosslinking agent comprising a compound having at least two noncyclic acid anhydride groups and represented by the following formula ##STR1## wherein R is a monovalent hydrocarbon group having 2 to 50 carbon atoms, R' is a bivalent hydrocarbon group having 2 to 50 carbon atoms, the hydrocarbon groups R and R' containing or not containing an ether linkage, urethane linkage or ester linkage, and n is an integer of 1 to 500. The invention also provides a curable composition including (A) at least one resin selected from the group consisting of (i) a resin having at least one epoxy group and at least one hydroxyl group in the molecule, (ii) a resin mixture of a resin having at least two epoxy groups in the molecule and a resin having at least two hydroxyl groups in the molecule, and (iii) a resin having at least two epoxy groups in the molecule, and (B) the above-mentioned crosslinking agent.

We claim: 
     
       1. A curable composition comprising: (A) at least one resin selected from the group consisting of (i) a resin having at least one epoxy group and at least one hydroxyl group in the molecule, (ii) a resin mixture of a resin (ii-1) having at least two epoxy groups in the molecule and a resin (ii-2) having at least two hydroxyl groups in the molecule, and (iii) a resin having at least two epoxy groups in the molecule, and (B) a crosslinking agent having at least two noncyclic acid anhydride groups and represented by the following formula ##STR5##  wherein R is a monovalent hydrocarbon group having 2 to 50 carbon atoms, R' is a bivalent hydrocarbon group having 2 to 50 carbon atoms, the hydrocarbon groups R and R' containing or not containing an ether linkage, urethane linkage or ester linkage, and n is an integer of 1 to 500.   
     
     
       2. A composition as defined in claim 1 wherein the resin (i) has 2 to 50 epoxy groups and 2 to 50 hydroxyl groups in the molecule. 
     
     
       3. A composition as defined in claim 1 wherein the resin (i) is about 300 to about 100000 in number average molecular weight, 
     
     
       4. A composition as defined in claim 1 wherein the resin (ii-1) has 2 to 50 epoxy groups in the molecule, 
     
     
       5. A composition as defined in claim 1 wherein the resin (ii-1) is about 300 to about 100000 in number average molecular weight. 
     
     
       6. A composition as defined in claim 1 wherein the resin (ii-2) has 2 to 50 hydroxyl groups in the molecule, 
     
     
       7. A composition as defined in claim 1 wherein the resin (ii-2) is about 300 to about 100000 in number average molecular weight, 
     
     
       8. A composition as defined in claim 1 wherein the resin (iii) has 2 to 50 epoxy groups in the molecule, 
     
     
       9. A composition as defined in claim 1 wherein the resin (iii) is about 300 to about 100000 in number average molecular weight. 
     
     
       10. A composition as defined in claim 1 wherein the ratio of the component (B) to the component (A) is about 1 to 1000 parts by weight of the component (B) per 100 parts by weight of the component (A). 
     
     
       11. A composition as defined in claim 1 wherein a curing catalyst is further added to the component (A) and the component (B).